Both businesses and households rely on electrical equipment powered from one-phase, two-phase, three-phase, or other suitable utility-provided alternating-current (AC) power sources. However, commercial power reliability may not suffice for certain applications, for example, for computer facilities, hospitals, banking systems, or industrial motor loads. Therefore, a backup—or even an independent—local power source may be desirable to supplement or substitute for a utility-provided AC power source.
One type of a local power source is a static system, which typically uses an inverter to generate the load's AC power from a direct current (DC) battery bank. Providing power from such a static system for an extended period of time, however, may require a large and costly bank of batteries. Another type of local power source is a rotary system, which typically uses a gasoline or diesel engine to rotate the shaft of an AC generator to produce an AC load current for an extended period of time. In such a system, a providing a stable output voltage signal typically requires a constant rotational shaft velocity. However, load-switching, motor-starting, or other load variations may perturb shaft velocity and, in turn, may perturb the stability of the output voltage signal. A mechanical flywheel storing kinetic energy may assist in maintaining a constant shaft velocity may be maintained by storing kinetic energy, such as in a mechanical flywheel. However, this, provides a bulky, costly, and inefficient solution. For these and other reasons, the present inventors have recognized a need for an improved backup and/or substitute local AC power source.